MCUboot partition for Zephyr

RE: MCUboot partition for Zephyr

Hung Bui — Thu, 06 Jan 2022 15:50:55 GMT

Hi Andreas,

2. The information I got from the developer is that Direct XIP is available in MCUBoot but we haven't integrated it in to NCS. So in theory it's possible to do what you are planning but we haven't tested that. In addition you would need to compile the smaller application and the real application to start at a dedicated location, it's something we haven't tested.

So all in all I would suggest to go for the external flash solution.

RE: MCUboot partition for Zephyr

Hung Bui — Wed, 05 Jan 2022 16:32:12 GMT

Hi Andreas,

1) Yes it's possible. If you can add external flash to the board then you can configure MCUBoot to use the external flash as secondary slot. You can have a look at this case: https://devzone.nordicsemi.com/f/nordic-q-a/72543/mcu-boot-with-external-flash-littles-partition-and-secondary-image-partition

2. This is a good idea. But I'm not 100% sure if it's supported by MCUBoot and by Nordic implementation. You can have a look at the DirectXIP section here. I will need to check with our team to see if #1. You can use Direct XIP 2. You can configure Slot 1 larger size than Slot 2.

I will keep you updated.

RE: MCUboot partition for Zephyr

AndreasM — Wed, 05 Jan 2022 13:00:37 GMT

What about following solutions:

1.) Can we use an external Flash to store one of the images?

2.) Can we do the update in two steps. First download a smaller application, that only has the BLE function to download a bigger file with the real application. The benefit would be, that we do not need two images with the same size rather have to images with different size they may overlap.

RE: MCUboot partition for Zephyr

Hung Bui — Wed, 05 Jan 2022 08:43:08 GMT

I'm afraid that we don't have any other solution besides trying to optimize the code.
Another option is to use the nRF5 SDK and Softdevice. The Softdevice is still a good option with most of the features in Bluetooth 5.2 supported. Of course porting the application back to nRF5 SDK would require considerable amount of work, depends on the application.

RE: MCUboot partition for Zephyr

AndreasM — Tue, 04 Jan 2022 15:58:24 GMT

Thank for the answer

Unfortunately we cant reduce the application size and we already upgraded from nFT52810 to the bigger nRf52832. To go bigger is a cost issue.

To separate the Zephyr part was the last hope. We have to face it and negotiate with the customer. Update seems not feasible with this constellation.

RE: MCUboot partition for Zephyr

Hung Bui — Tue, 04 Jan 2022 14:18:00 GMT

Hi Andreas,

There is a difference between the Zephyr architecture and our legacy softdevice architecture that Zephyr's stack is not separated from the application. So it's not possible to have a dedicated "stack" area that will not get updated.

So in this case you really need to suggest the customer to reduce the size of the application. Is there any static data that was included in the application that can be moved to the storage area ?
Another option is to move to a chip with larger flash size, the nRF52840 for example.